Skateboarding has become a popular recreation and sport. Derived from the late-1940's surfing scene in California as an activity for when the waves were flat, early skateboards were comparatively primitive devices comprising wooden boxes with roller skate wheels attached to their bottom surface. Eventually, the boxes were replaced by wooden planks with metal or “clay” wheels. In the early 1970's, polyurethane wheels providing significantly improved traction and performance were introduced. Such skateboards were easier to ride, increasing the popularity. Today, skateboarding represents a $4.8 billion industry with more than 11 million active skateboarders in the world. It will become an Olympic event in 2020.
The user stands with his feet on the skateboard and uses one foot to manually propel the skateboard forward. The skateboard can also be ridden downhill using gravity to propel the device.
A modern skateboard typically features a deck that is 7-10½ inches wide and 28-33 inches long. “Long” boards are usually over 36 inches long. Two metal trucks connect the wheels to the bottom surface of the deck. The wheels of the wheel assemblies rotate along an axle that runs through the hanger portion of the truck. A baseplate forms the top portion of the truck and is used to mount the truck to the deck. Rubber bushings positioned between the baseplate and the hanger cushion the truck when it is turned. Each of the wheels is mounted on its axle via two bearings.
The wheel truck assemblies are typically mounted to the skateboard in a fixed relationship without any ability to pivot the wheels to steer. Instead, the user must lean sideways while riding the skateboard to shift his center of gravity away from the skateboard to turn the skateboard to the left or right. This action requires balance and coordination by the user and can provide challenges to a beginner or novice rider.
The need for a more-maneuverable skateboard arises for a user who is engaging in skateboard tricks which has become a sport in its own right. Once content with two-dimensional freestyle tricks such as wheelies, manuals, and pivots, popular skateboard tricks have become more complicated, three-dimensional, aerial maneuvers. For example, an “ollie” jump is accomplished by snapping down the tail of the skateboard and sliding the user's front foot forward to launch the skateboard in the air. While floating in the air, the user can use his hand to hold the skateboard against his feet in a maneuver called an “indy grab,” Often times, aerial rotations are combined to produce a “kick flip.” Riding the skateboard's deck or truck along a street curb, ledge, or rail yields a “slide” or “grind,” respectively. Specially-built skateboard parks with ramped surfaces provide the perfect environment for these highly imaginative and acrobatic aerial maneuvers, which require the user to produce quick turns on his skateboard.
U.S. Pat. No. 4,955,626 issued to Smith, et al. discloses a device comprising two skateboards connected to each other by means of a spacer element. The user stands with his left foot on the one skateboard and his right foot on the other skateboard. By shifting body weight relative to the two feet, the user can pivot the skateboards inwards or outwards with respect to the longitudinal direction of travel to execute a turn. But this device requires more balance and coordination then many users can muster.
U.S. Pat. No. 6,511,083 issued to Tsai discloses a skateboard featuring a rear wheel assembly that is fixed with respect to the longitudinal axis of the deck, and a front wheel assembly that pivots with respect to the longitudinal axis by means of a steering shaft that extends vertically from the deck. While convenient for a user riding along a street or sidewalk for recreation, this steering shaft can interfere with aerial trick maneuvers. It can also provide a safety hazard to the user.
U.S. Pat. No. 3,069,182 issued to Hufford in 1962 provides an example of a four-wheeled coaster wagon that a user rides in along a downwardly-ramped surface. The front axle assembly is mounted to turn by means of a handle bar around a vertical bolt with respect to the wagon carriage. A disc positioned between the carriage and wheel assembly provides high resistance against the front axle turning when a wheel strikes an obstruction. A compression spring connected between this disc and the bottom of the chassis of the wagon further limits the degree to which the front axle may be turned upon impact with an impediment, and biases the front wheels to their centered position. However, the limited ability of the compression spring to pull the front axle back to its “true center” position is acceptable, because the user may easily use the handle bar to steer the wagon.
More advanced skateboarders demand skateboards that are more maneuverable to allow them to perform tricks like jumps and spins. U.S. Pat. No. 4,160,554 issued to Cooney discloses a conventional skateboard having non-pivotable front and rear axle assemblies, but with a “lazy Susan”-like rotating disk mounted to the top surface of the board. The user stands on top of the disk and can turn the disk and his body with respect to the independently moving skateboard as it is propelled by the user's foot in a linear direction. But the user still must rely upon leaning towards the left or right sides and shifting his weight with respect to the longitudinal axis of the skateboard to turn it, because rotating the disk does not rotate the front or rear axle assemblies. Thus, the skateboard according to Cooney does not provide the kind of maneuverability required for tricks. This is particularly the case for novice skateboarders. See also U.S. Pat. No. 4,230,330 issued to Muhammed.
U.S. Pat. No. 3,771,811 issued to Bueno does disclose a skateboard exhibiting some degree of axle maneuverability. The front axle assembly is fixed with respect to the longitudinal axis of the skateboard. The rear axle assembly pivots with respect to the skateboard and is mounted to a circular platform above the top surface of the board. The user places his left foot on the front portion of the board, and his right foot on top of the circular platform. By turning his right foot, he pivots the circular platform and the rear axle assembly mounted thereto in a crude manner to turn the skateboard. However, the user's right foot is positioned above the left foot which can throw off balance. Moreover, the large circular platform extends from the rear end of the skateboard, which interferes with the downward stomp exerted by users on the rear end of the board necessary for executing jump tricks. It is also difficult for the user to control the maneuverability of the rear axle assembly given the simple nature of the mechanism, nor does the axle assembly return to its true forward-facing position on its own.
U.S. Pat. No. 4,202,559 issued to Piazza, Jr. discloses a similar skateboard construction, but where the rear axle assembly is fixed with respect to the longitudinal axis of the skateboard, while the front axle assembly is pivotably mounted to the board by means of a hollow bearing that passes through a bearing collar affixed to the circumference of a hole formed in the board. A steering platform rests on top of the hollow bearing and above the skateboard. A torsion spring is positioned inside the hollow bearing with one end connected to the steering platform and its other end connected to the skateboard to limit the radius of pivotable steering of the front axle. The user stands with his right foot on top of the steering platform and can turn the platform with his foot to pivot the front axle assembly. When the user releases the rotational force applied to the steering platform, the torsion spring “tends to act to return the steering platform to its normal standby orientation.” But this single torsion spring only provides limited ability to bias the steering platform and its axle.
U.S. Pat. No. 8,608,185 issued to Dermal discloses a skateboard truck assembly with an integrated combination of gears resembling planetary gears that allow both wheels and a caster to remain on the ground while the skateboard travels along the longitudinal axis. When the user leans to the left side or right side, the gear assembly causes the “downhill” wheel to rise in the air and the caster to be displaced so that the user can slide or drift laterally as though he were riding a snowboard down a ski slope. The raised downhill wheel will not catch any street irregularities or rocks that would stop the skateboard from rolling. While this type of skateboard provides a degree of lateral sliding maneuverability, it does not al low an axle assembly to be directly pivoted by the skateboarder with his foot to turn the skateboard.
U.S. Pat. No. 8,925,936 filed by one of the inventors of the present Application and owned by the Applicant of this Application discloses a skateboard having a user engagement member rotatably mounted inside the board that is directly connected to the truck and axle assembly. The user engagement member can be operated by the foot of a user standing on top of the moving skateboard. With two such truck and axle assemblies mounted to the skateboard, the user may turn the front and rear axles independently of each other. The trucks can be rotated 360°. But, the user still must keep track of the pivoted position of each axle with respect to the longitudinal axis of the skateboard to counter turn the user engagement member to return the axle hack to its standby, forward-facing position after a turning or spinning maneuver has been executed before approaching the next maneuver. It can be difficult to counter turn the user engagement members to the axle's standby position necessary to achieve this “true north” position while the skateboard is moving, which can harm the user's confidence in executing tricks. Moreover, a skateboard having its two axle assemblies pointed in different directions will typically provide an unstable ride with the tip or tail of the skateboard nose diving. This increases the risk of wipeouts and injury to a beginner or skilled user.
Meanwhile, scooters are popular recreational vehicles for children. Consisting generally of a narrow foot board mounted between two wheels tandem with an upright steering handle attached to the front wheel, the child places one foot on the scooter board, while using the other foot to push off the ground to provide the necessary motive force. The steering handle provides direct maneuverability to the user of the front wheel. But the turned wheel does not return to its “true north” position unless it is counter turned by the user.
Thus, it would be beneficial to produce a skateboard or scooter structure having independently pivotable front and rear axle assemblies mounted to foot disks operatively turned by the user's feet standing on top of the moving skateboard where the axle assemblies automatically are returned to their true north positions with respect to the longitudinal axis of the board when the turning force is released from the user foot disks within the board. Likewise, a scooter having a front wheel that is maneuvered by a steering handle coupled with a north-seeking return mechanism when the user no longer is exerting turning force on the steering handle would also be highly beneficial.